Since the prognosis of FS seizures with different clinical features differs significantly, FS is classified into simple febrile convulsions (SFS) and complex febrile convulsions (CFS) according to the clinical features. SFS must meet the following four conditions: (1) the convulsions are generalized, mostly generalized tonic-clonic seizures; (2) the seizures are self-limiting, manifesting as short duration seizures (<15 min); (3) there is usually only one convulsive seizure in a febrile course; (4) no abnormal neurological signs remain after the convulsions. In contrast, FS seizures with any of the following characteristics are referred to as CFS: (1) prolonged convulsive seizures lasting more than 15 min; (2) multiple convulsive seizures during a single febrile episode or within 24 h of onset; (3) confined convulsive seizures, which may manifest as focal seizures with the following characteristics: clonic and/or tonic components; atonic seizures; starting on one side, secondary or no generalized seizures. head and/or eye deviation to one side; and the presence of temporary limb movement disturbances after the seizure. Due to immaturity of the brain, long duration convulsive seizures are prone to occur in childhood, and some people also further classify CFS according to the duration of convulsive seizures, and refer to CFS with convulsive seizures lasting more than 15 min as long duration febrile convulsions (PFS). CFS with convulsive seizures lasting more than 30 min is known as febrile convulsion continuum (FSE). Notably, FSE can occur in 5% to 9% of children with FS; FSE is the cause of 25% of children with convulsive persistence in childhood and has been reported to account for 2/3 of convulsive persistence in children aged 1 to 2 years.